This invention relates to the detection of the onset of sleep in a human being and more particularly to such detection by monitoring temperature variations within the auditory canal.
There has been a long-standing need for reliable techniques to detect the onset of sleep. Such techniques would be particularly advantageous for preventing accidents by those who drive trucks or cars for long periods of time or operate other potentially dangerous machinery. Prior approaches for detecting the oncoming condition of sleep and thereafter stimulating the subject to prevent an accident have not been altogether satisfactory. Techniques which monitor such parameters as a subject's eye movements, breathing rate, electroencephalogram, or electrocardiogram are cumbersome and are often incapable of detecting reliably the onset of sleep. Similarly, a so-called dead man's grip which senses relaxation of the subject's grip to indicate a sleep state, although not difficult to implement, may not respond soon enough to prevent an accident.
In occupations requiring mental alertness such as air traffic control, it is likewise desirable to detect a diminution in mental acuity short of the subject's actually falling asleep so that he may be replaced by someone more mentally alert. Heretofore, there has been no simple and reliable way of detecting the often subtle degradation in alertness.
It is therefore an object of the present invention to provide apparatus for detecting the onset of sleep which is reliable, easy to implement and which interferes minimally with the subject's comfort and mobility.
It is a further object to provide apparatus capable of detecting a falloff in mental alertness in a human subject.